---
id: china-migration
title: 春节人口迁徙
---

### 一个简单的示例

```jsx live
function render(props) {
  const container = useRef(null);

  const dataUrl = useBaseUrl('/json/china-migration.json');
  const airlineUrl = useBaseUrl('/json/china-airline.json');

  // 经纬度获取
  function getGeoCoord(geoCoord, name) {
    const city = name.split('_').pop();
    if (city) {
      const coord = geoCoord[city];
      return coord;
    }

    return null;
  }

  // 线路获取
  function getLineCoord(geoCoord, fromname, toname) {
    if (fromname && toname) {
      const _start = fromname.split('_').pop();
      const _end = toname.split('_').pop();
      if (_start && _end) {
        const fromCoord = geoCoord[_start];
        const toCoord = geoCoord[_end];
        return {
          fromName: _start,
          toName: _end,
          coords: [fromCoord, toCoord],
        };
      }
      return null;
    }
    return null;
  }

  const initChat = (map, option) => {
    const chart = new EChartsLayer(option, {
      stopEvent: false,
      hideOnMoving: false,
      hideOnZooming: false,
      forcedPrecomposeRerender: true,
    });

    chart.appendTo(map);
  }

  const init = async () => {
    const map = new ol.Map({
      target: container.current,
      view: new ol.View({
        projection: 'EPSG:4326',
        zoom: 5,
        rotation: 0,
        center: [113.53450137499999, 34.44104525],
      }),
      layers: [
        new TileLayer({
          source: new XYZ({
            url: 'https://{a-c}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png',
          }),
        }),
      ],
    });

    function convertData(sourceData) {
      return [].concat.apply(
        [],
        sourceData.map((busLine) => {
          let prevPoint = null;
          const points = [];
          const value = busLine.shift();
          for (let i = 0; i < busLine.length; i += 2) {
            let point = [busLine[i], busLine[i + 1]];
            if (i > 0) {
              point = [prevPoint[0] + point[0], prevPoint[1] + point[1]];
            }
            prevPoint = point;
            points.push([point[0] / 1e5, point[1] / 1e5]);
          }
          return {
            value,
            coords: points,
          };
        }),
      );
    }

    const geoCoord = await fetch(dataUrl).then(res => res.json());
    const data = await fetch(airlineUrl).then(res => res.json());

    const option = {
      backgroundColor: 'transparent',
      title: {
        text: '春节人口迁徙',
        x: 'center',
        y: 'top',
        textStyle: {
          color: 'white',
        },
      },
      legend: {
        show: true,
        selected: {},
        x: 'left',
        orient: 'vertical',
        textStyle: {
          color: 'white',
        },
        data: [],
      },
      series: [
        {
          name: 'Migration',
          type: 'lines',
          effect: {
            constantSpeed: 30,
            show: true,
            trailLength: 1,
            symbolSize: 1.5,
            color: 'rgba(204, 246, 255, 1)',
          },

          itemStyle: {
            lineStyle: {
              color: 'rgba(2, 166, 253, 1)',
              type: 'solid',
              width: 0.5,
              opacity: 0.4,
            },
          },
          data: [],
        },
        {
          symbol: 'circle',
          type: 'effectScatter',
          symbolSize: 1.5,
          itemStyle: {
            color: 'rgba(255, 0, 0, 1)',
          },
          data: [],
        },
      ],
    };
    data.allLine
      .sort((a, b) => b.num - a.num)
      .slice(0, 3000)
      .forEach((line) => {
        const callData = getLineCoord(geoCoord, line.start, line.end);
        if (callData) {
          option.series[0].data.push();
        }
      });
    option.series[1].data = data.topCityOut.map((point) => ({
      value: getGeoCoord(geoCoord, point.name),
    }));

    initChat(map, option);

    function resize(target) {}

    return {
      resize,
    }
  }

  useEffect(() => {
    const { resize } = init();

    return () => {
    };
  }, []);

  return (
    <div className="live-wrap">
      <div ref={container} className="map-content" />
    </div>
  );
}
```
